Calculating appliance.



G..W. EVANS-GROSS. GALCULATING APPLIANGE.

APPLICATION FILED MAR.12,1907.

91 3 ,4:83 Patented Feb. 23, 1909.

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G. W. EVANS-GROSS.

GALGULATIN G APPLIANGE.

APPLIOATION FILED 11,111.12, 19.07.

913,483. l Patented Feb. 23, 1909.

2 SHEETS-SHEET 2.

. N ee' NTTED STATES PATENT OFFICE.

GEORGE W. EVANS-CROSS, OF BALHAM, ENGLAND.

CALCULATING APPLIANCE.

To all whom it may concern:

Be it known that l, GEORGE WILLIAM EvANs-CRoss, a subject of the King ofGreat Britain and Ireland, residing at 22 The Boulevard, Balham, in thecounty of Surrey, England, have invented certain new and usefulImprovements in Calculating Appliances, of which the following is aspecification, reference being had therein to the accompanying drawings.

This invention relates to an appliance designed to facilitate thedetermination of interest on different principal sums, at diierent ratesper cent., and for different periods of time, wherein the interest onthe various principals for various times is tabulated on a ase plate atone standard rate per cent. only and there are provided in combinationwith the base plate auxiliary scales or tables movably mounted thereon,whereby the interest at other rates per cent. can be determined from thetablel on the base plate.

The accompanying drawings show an apparatus according to this invention.

Figure 1 is a plan of the main base plate Fig. 2 is a plan of the mainand auxiliary slide plates mounted upon this base plate and adapted toslide thereon; Fig. 3 is a plan of the auxiliary base plate; Fig. 4 is aplan showing the base plate with various scales in position thereon;Fig. 5 is a longitudinal section through the base plate on the line V-Vof Fig. 4; Fig. 6 is a transverse section through the base plate and itsscales on the line VT-VT of Fig. 4; and Figs. 7 and 8 are views ofshields hereinafter referred to.

On the base plate a there is tabulated in successive horizontal linesthe interest at a standard rate of 2?,- or 10 quarters er cent. and to adegree of accuracy su icient in practice on the series of principalshown on the horizontal line l) of Fig. 2 for periods ranging from oneto twenty-four days. The upper auxiliary scale or slide-plate mounted onthe base plate a and adapted to slide thereon contains besides theseries of principal sums l) already mentioned, a second series ofprincipals c. The monetary units emloyed in the tables shown are the s.d. and farthings of the English coinage; the principals shown at l)ranging from HU to 95; from 1 to 9; from 10 to 90 and from .100 to 1000;While those shown at c are similarly arranged except that the series off tenths of 1 to the left are omitted.

In the columns of the base a vertically Specification of Letters Patent.

Application iiled March 12, 1907.

Patented Feb. 23, 1909.

Serial No. 362,077.

over the respective principal sums of b and c the interest on these sumsfrom one to twentyfour days is indicated in pounds, shillings,

pence and farthings, the latter for the sake of s compactness beingindicated by small iigures above the pence. Beneath the scales l) and cthere is arranged to slide the auxiliary scale or under-slide d shown inFig. 3, one horizontal line, say for example the line c being visiblethrough the slot f between the scales b and c (Fig. 2). On the scale dthere is tabulated on successive horizontal lines, and vertically underthe series of principals c, four, i'ive, six, seven, eight, nine,eleven, &c. up to sixteen-tenths of these principals, corresponding to1, 131i, 1f; up to 4 per cent. as shown in the vertical column g andhereinafter more fully explained. For the salie of clearness tenths ofare indicated by small 'figures written above the integers; thus theentry at the to left-hand corner denotes .04U. At the left of Fig. 1 isshown a slide rule or scale of dates 7L which enables the interestbetween two given dates to be ascertained without having to count thenumber of intervening days.

The manner in which the tables a, b, c and d are assembled, and appliedto the solution of an interest problem is illustrated in Figs. 4, 5 and6. adjusted for the solution of the problem hereinafter' stated by wayof example. The scales l), c, d and the support l on which these scalesare mounted slide in the grooves 7c (Fig. 5). These scales and supportmay conveniently be of cardboard, the scale d being adapted to slidebetween the support Z and the scales b, c so as to exhibit one or otherof its horizontal lines through the aperture TWith regard to thedetermination of interest at the standard rate of 211- or l per cent.;the amount can be read off directly from the base plate a, the principalbeing indicated by sliding indicators m on the scale b. For example: Letthe interest be required, at 23,- per cent. on .6966.140 for the periodbetween January 2nd and 6th. First adjust the scale of dates as shown inFigs. 1 and 3, then set the indicators m to 900, 60, 6, and 1%-, andadjust the scale l) to the line corresponding to January 6 on the baseplate. The interest, shown on the base-plate above the indicators m4s.11d.+4d.}-d.l- 0 s-d. For the determination of interest at other thanthe standard rate, the auxiliary scales c and d are employed. Forexample, let

In Fig. 4 the scales b, c and CZ are `into view through the aperture fthe line c corresponding to l per cent. and having thereon TTU of theprincipals on the scale c. The given principal, 1000 +300 +80 1 is thendenoted by the indicators n on the scale c and the auxiliary principal7O0-l-21O-t56+{%=966175 is read off on the line e (Fig. 1l). hisauxiliary principal is Y then indicated by the indicators m on the scaleb whereupon the desired amount of interest is read oil1 from the baseplate 5s. 2d. lt will be observed that no zeros have been provided sothat it would be difficult to indicate, say on the scale c, 1301. Toobviate this difficulty while economizing the space that would be takenup by zero columns, there are provided small shields p oli' the formshown in Figs. 7 and 8 adapted to be placed over the indicators m or n.Gne of these shields would for instance in the case mentioned be placedupon the indicator n standing at .80 on the scale c thus showing that noreading is to be taken at this indicator. lt will be understood that thestructural details of an appliance in accordancewith my invention may beconsiderably modilied without departure from the principle thereof.

lWhat I claim is A calculating appliance for the computation of intereston a given principal at a given rate per cent. and for a given period,

comprising a main baselate having tabuf lated thereon in verticasections and columns and in horizontal lines the amounts of interest ata standard rate per cent. on various principals and for various times,each vertical column containing the interest at such standard rate on agiven principal for successively increased periods of time and eachhorizontal line the interest for the same period on successivelyincreasing principals; a slide rule arranged parallel to said columnsand graduated to represent the times Afor which interest is tabulated insaid columns, a

slide-plate arranged on said base-plate parallel to said lines andmovable thereon parallel to said columns, said slidelate being graduatedsimilarly to said co umns and bearing under eacli column the principalsum wnereon the interes t is tabulated in said column g slidingindicators longitudinally movable on said slide-plate, an auxiliaryslide-plate mounted on said base-plate and bearing a series of principalsums and an auX- iliary slide plate likewise mounted on said mainbase-plate and adapted to move under said auxiliary baselate and havingtabularly arranged in co umns and lines a series ol' proportional partsof those sums 3 and sliding indicators movable lengthwise of the saidauxiliary slide plate.

In testimony whereof l allix my signature in the presence of twowitnesses.

G. W. EVANS-CROSS.

